Biological cell trapping and manipulation of a photonic nanojet by a specific microcone-shaped optical fiber tip

Trapping and manipulating mesoscopic biological cells with high precision and flexibility are very important for numerous biomedical applications. In particular, a photonic nanojet based on a non-resonance focusing phenomenon can serve as a powerful tool for manipulating red blood cells and tumor cells in blood. In this study, we demonstrate an approach to trap and drive cells using a high-quality photonic nanojet which is produced by a specific microcone-shaped opticalfiber tip. The dynamic chemical etching method is used to fabricate optical-fiber probes with a microcone-shaped tip. Optical forces and potentials exerted on a red blood cell by a microcone-shaped fiber tips are analyzed based on finite-difference time-domain calculations. Optical trapping and driving experiments are done using breast cancer cells and red blood cells. Furthermore, a cell chain is formed by adjusting the magnitude of the optical force. The realtime backscattering intensities of multiple cells are detected, and highly sensitive trapping is achieved. This microconeshaped optical fiber probe is potentially a powerful device for dynamic cell assembly, optical sorting, and the precise diagnosis of vascular diseases.